As a method for producing a β-oxonitrile derivative or an alkali metal salt thereof by reacting a nitrile compound with a carboxylic ester, there has been disclosed a method, for example, in Romania Patent No. 71248 (RO 71248), in which butyl acetate and propionitrile are reacted in the presence of sodium butoxide in xylene at 125 to 128° C. to obtain an alkali metal salt of α-acetylpropionitrile with a purity of 85 to 87% and a yield of 70 to 75%, and neutralizing and purifying the product to obtain α-acetylpropionitrile with a yield of 50%. Also, in Chemische Berichte (Chem. Ber.), 115, 355 (1982), there is disclosed a method for obtaining 2-methyl-3-oxobutane nitrile by reacting ethyl acetate and propionitrile in the presence of sodium hydride in benzene with a yield of 34%, and further in Journal of American Chemical Society (J. Am. Chem. Soc.), 79, 723 (1957), there is disclosed a method for obtaining 2-methyl-3-oxobutane nitrile by reacting methyl acetate and propionitrile in the presence of sodium amide in liquid ammonia with a yield of 63%.
However, in either of the methods, their yields are low and they are not a method satisfied as an industrial preparation process.
An object of the present invention is to solve the above-mentioned problems and to provide a process for preparing a β-oxonitrile compound or an alkali metal salt thereof which is capable of obtaining a β-oxonitrile compound or an alkali metal salt thereof with a high yield and suitable for industrial preparation process.